David Hasselhoff defends Justin Bieber for punching fan

Actor David Hasselhoff has jumped to Justin Bieber's defense, insisting the pop star was right to punch a fan who invaded his personal space in Spain.

The unnamed devotee startled the singer when he grabbed at him through an open car window as Bieber arrived at a gig in Barcelona on Tuesday (22Nov16).

The Baby star reacted quickly and punched the man, leaving him with a bloody lip.

Justin's actions have split fans and critics alike, but Hasselhoff insists he would likely have done the same had he been in a similar position, because some overzealous fans lack the respect stars deserve.

The Baywatch icon weighed in on the incident during an appearance on U.K. show Good Morning Britain on Wednesday (23Nov16), when Hasselhoff sided with host Piers Morgan.

"I agree with you, Piers, he should have punched that guy out," the 64-year-old said. "Fans are whacked out, man.

"Come on, what's that guy want, an autograph he can sell? He's going to get his face punched out. You need to treat us with respect, and you will get respect back."

Recalling some of his own crazy encounters, Hasselhoff added, "I've had fans chase (me). I've had fans jump in my car and pretty much terrify me."

Bieber has become very aware of his crazy fans in recent days - last week (ends18Nov16) one devotee pulled Justin's trousers down during an incident in Prague, Czech Republic, and a bodyguard had to rush to the embarrassed singer's rescue.

The superstar was in Barcelona as part of his ongoing Purpose World Tour. He will wrap up the European leg of his trek with a pair of dates at London's O2 Arena on 28 and 29 November (16), his final shows of the year (16).